Supposedly, termites make a distinct smell, but I don't know what it smells like. Wool moths smell like cat pee.

DanJ, did you solve your mystery odor? I'm having similar problems. About a month and a half ago I noticed a faint moldy peanut smell in my house. I cleaned like crazy while looking for the source but never found it. Two weeks later the smell was stronger, especially in my bathroom. I checked for mold, leaks, air system checked, and found nothing wrong, but smell still there. Then last week I developed a cold and didn't respond to any of the medication. I still have excessively red, watery eyes, sinus congestion and dry cough. Then started itching a few days ago but nothing new in house to be allergic to. Smell stronger than ever. Getting seriously worried.

-Janillo

Janillo, Could it be some of that hardwood flooring from Lumber Liquidators with the formaldehyde in it? Or a new piece of furniture?

Good idea but no new flooring or furniture. Some small-scale remodeling but that was nearly 1 yr ago. I tried flushing drains as one post suggested and it did seem to help (that or wishful thinking). Thanks!

We had a bad outhouse smell in our bathroom, and I scrubbed and scrubbed the toilet, and even pulled the toilet and replaced the wax ring, all to no avail. I figured out the smell was coming from the toilet brush and holder that I stored in the cabinet. Duh? It's in the garage now. Someone needs to train dogs to pinpoint the source of smells.

Again another poster asks for help and never leaves a message telling how the problem was solved. People take there valuable time to help and the OP never gives a clue to what the problem was. I doubt they are still having a smell after 2 years. Maybe they sold the house.

Yes, it would be nice to hear how the first person solved their problem. We have not solved our mystery. The odor we have also resembles burning plastic and it occurs only on sunny days (even when it's very very cold outside). Looking back at the calendar, I noticed that it began on the first sunny day after a huge snowfall and persisted throughout the winter while the roof was covered with snow. Now that the snow has melted from the roof, the odor has largely faded. I'm not sure what that means and whether it will happen again next winter. Wondering if some roof vent was blocked by snow or ice? Some posters have suggested mold, but I am wondering if mold can smell like burning plastic? Should I get a roof person over or an indoor air tester?

lydchambers, I bet you're right about snow blocking a roof vent. Maybe you could go in your attic, and see if the attic smells like that -- then you'd know the smell was coming from the attic.

@southerncanuck, I think we can only assume that the original poster's smell was something far more sinister than anyone suspected, and it has her tied up in the basement or something.

I am experiencing this same smell as DanJM. It smells like a chemical (toxic) or maybe burning plastic like comment up above. It happens when sun is shining on the east side of the house. We have 2 old inside wood dining room windows with varnish on them. Once the sun moves to the south side of the house the smell gets less intense. Sometimes, I can smell it upstairs. It goes away after a while but would like to know what it is to make sure it is not harmful. I thought about calling a window retailer to check it out. Perhaps new windows would help.

Old windows with old varnish are not going to give off odors unless they are leaking and the wood is rotting. It has to be something else.

I have the same issues. Pungent smell, feel like something biting. Have bite marks. Mite or something. I feel its more airborne. Fungus or parasite. Takes shape in other object. Have waxy feeling on skin, or floor, other furniture.

Lydchambers and sdolly, Did you figure out your problem? I am having the same problem now...only when it is sunny. I have a metal roof and i am wondering if the sun on the metal is making some wiring too hot.

There should not be wiring right up under the roofing, though. And wiring should be able to handle any reasonably expected attic temperature - which is very hot.

We had/have the same issue! It smells like ammonia or cat urine in our 2nd level masted bedroom (facing west). It only smells in the winter, after it's been freezing cold outside (we live in Canada) and in addition to when the sun comes out and shines on our bedroom wall. The sun is very intense and causes the snow to thaw. The smell is defiantly coming from our walls. We took the trim off our window to smell inside of the wall and stink hit us in the face. We called our builder (as our house is only 3 years old) and they did a test for moisture in the walls (there is a laser probe that they place on the wall to measure moisture within the wall). Sure enough, water was in the walls - Caused from improper insulation around the windows, causing condensation which was causing water build up inside the walls. They tore the wall out (smell was awful and definitely from inside the wall) and we think the smell was caused by the moist batt insulation being heated by the sun. The batt insulation does infact have ammonia as one of the ingredients. Once they changed out the old insulation for new and sealed the wall back up -VIOLA! The cat pee smell was gone. We were so relieved! That was last year. Now it's winter again and the smell is back!!! We are beside ourselves. We are going to do another wall sensor test to see if there is moisture in our walls again. If so- than our original thoughts of the cause for the smell were correct. If there isn't moister in the walls, we are back to square one. What a mess. Keep you posted.

Found this article on insulation. Extreme temperatures as well as dampness cause some insulation to off-gas unpleasant smells!

http://www.ct.gov/dph/lib/dph/environmental_health/eoha/pdf/insulation_fs1__2014_rev.pdf

We have been getting a terrible fishy smell in our hallway,,we thought it was coming through the vents,checked that and found nothing,it only seems to happen when our hallway ceiling light is left on for more than an hour or so,and until i saw these posts i couldn't believe it could be coming from the ceiling light,but it is,,what is the cause?,and is there an easy remedy please,we are in the UK,and in a downstairs flat,johnty.

I am comforted to hear that others are having a similar problem to mine but its unfortunate this is happening. I have the same problem as the original post. My house is a new build approx 5 years old. I finished part of the basement during the summer months. In late autumn to early winter I detected a strong smell in the finished part of my basement. I had been using the basement without any odour for several months prior to this. The smell would be difficult to detect or absent on some days and very strong on other days. The smell is difficult to describe but I would say it smells like a acidic, pungent smell almost like electronic component failure without the burning smell. I would describe it as a leaking capacitor or burnt plastic. I tried disassembling my electronic components to look for damage. I tried cutting all power to the basement. I spent a lot of time sniffing to find the source. I asked all my friends for advice. I am baffled. What is interesting is that this smell will only present during a SUNNY DAY. It is -26C outside on a February day as I type this so it has nothing to do with heat for outside. I thought that it might be the sun activating some plastic thermal breakown. I removed my plastic blinds on the windows facing the sun. No effect. I tried removing the silicone caulking in the inside of the window sills. No effect. I have tried stuffing pillows against the windows on the sills to block the sun. No effect. I have tried shutting off the furnace but the smell will develop. It is clear however that it only occurs on sunny days. By evening when the sun looses its strength the smell dissipates. I simply can not find the source of this smell. It is a bright sunny day and the smell is strong. I am at wits end. I have read all the comments and thought about many but they don't apply. Any advice would be extremely helpful.

I wonder if a trained dog could find the smell? But they would have to be trained for that particular smell, which is unknown.

I believe I have localized to odour from the wall the sun is shining on. I think it is coming from around the window casing. About three years ago I used arbourite veneered boards for the sills. I sealed the gaps between these boards and the 2x4 wall frame with expanding foam from a can. The drywall has been up since I bought the house. all this work has been done several years ago without any odour. As best as I can determine the odour is coming from the top of the window area which is two feet above grade. No other room in the basement has this odour. There are three other rooms, none with windows facing south like the one that the smell is coming from.

Hi again, we were having 2 smells. One was a hot smell, the other a musty, amonia or cat pee smell. Both smells were in an upstairs bedroom facing south. We have bad windows in our house. They are M&W windows through Plygem. I have many complaints about them but I will save it for another forum. We had to install storm windows on a 7 year old house. The hot smell we believe was caused by moisture building between the regular window and storm window. We cleaned the windows with windex and rubbing alcohol. We then opened the storm window a crack. Kind of defeats the purpose of storm windows but the smell is gone for now. We are still unsure about the other smell. We are guessing we have an issue with insulation. We will post again when we get it all figured out.

For people who change windows, walls, caulking...etc...

MAKE SURE YOU HAVE ENOUGH MONEY FOR MOST EXPENSIVE (and high quality) REPLACEMENTS AND THOSE SHOULDN'T BE FROM CHINA. Especialy anything CHEMICAL. Otherwise you are investing cash for nothing!

I've figured Chinese chemicals used in example caulking can easily REACT with certain environment conditions and you who have that stink somehow have trigered the condition and voila! The new house stinks!

By the way after buying Expensive replacements make sure the builder uses Your chemicals, not his.

TRY THIS: WHEN THE SMELL IS STRONGEST CLOSE ALL OUTSIDE DOORS, WINDOWS, AIR CONDITIONERS. AND THEN LIGHT A CIGARETTE BUT DON'T SMOKE. Walk slowly in the room where the smell is strongest and WATCH THE SMOKE. If it isn't STRAIGHT IT WILL POINT TO THE SOURCE OF STINK. It could be just about anywhere. Mark the source and with hammer and chissel SLOWLY AND CAUTIOUSLY BREAK WHATEVER IS HIDING THE SOURCE (HOLLOW WALL, FLOOR...)

Good luck Fido

Please explain how the cigarette smoke thing works. It sounds like you are suggesting to use it to detect drafts. However in that case you would be finding a place where warm air exits the house, so it does not seem that odors would be emanating from that spot INTO the building...

Any smoke is good but CIGARETTE SMOKE IS SAFEST (LEAST TOXIC) AND ALWAYS AVAILABLE (KEEP A PACK READY). People use polyurethane foam, caulking, various tapes thinking they prevent airflow. And they do, but it's never completely sealed.

What's the most recent change around house BEFORE smell appeared? Just that might get me to figure out what's the source.

PROBLEM SOLVED!!! Solution found!! I was scouring the internet for more information on this problem when I came across this posting. I included the link and the comments.

http://www.ablehomeinspection.com/services/special-investigations/

“For the last several years, whenever sunlight hit the back of my house, a strong odor would develop inside the house, which gradually made its way into every room. The problem seemed worse on days following rain storms, but the odor would be present regardless of the season, starting around noontime, and almost disappearing as dusk approached. During the Spring and Summer, the smell could become so bad I would not even enter some rooms.

In trying to resolve this, I had one contractor tell me it was a problem with mold growing on the foundation of my house. I rented a rotor-tiller, dug a trench to the bottom of the foundation, and must have poured hundreds of pounds of lime into the trench. I mixed it into the dirt, also used TSP to scrub the entire foundation, after breaking my back for 3 days, on the next sunny day, the scent returned. Another person thought it might be the heating system, my furnace was on its last legs so I had it replaced…no luck.

I had the rugs steam cleaned, had a plumber check for water leaks, and had rotor-rooter snaked out my sewer line, still the scent would not go away. I had the roof checked, while another contractor checked for rotted wood. No matter what I did the odor came back.

Finally, in January 2001, I went on the internet and did a search on “home inspections”. This brought up the site where Dennis offers his inspection service. I read about other homeowners who had other odd problems and Dennis was able to find solutions for them, so I figured I had nothing to lose….turned out to be the best idea I’d had in a long time.

Dennis traced the odor to the window screens which were made of fiberglass. He told me that the fiberglass screens were deteriorating from the sunlight and this is what was causing the odor. For almost 4 years, the various people I had checking for the odor were not close to discovering the source, Dennis found it in less than 10 minutes. If anyone I know ever has a problem with their home and needs an experienced building inspector….call Dennis, he doesn’t miss anything.”

Peter Porcello
Salem, MA 01970

(my comments) I covered the outside of my basement window for about a week with a piece of plywood to prevent the sun from shinning on the screen and the smell never returned. Shortly after that we had a dump of 45cm of snow. Several days later, after most of the snow melted I was able to remove the plywood and remove the window screen. The sun is shinning strongly on the window today and there is no hint of the pungent odour. I can't believe I have never heard of this problem before. This is only going to be a $10 fix to get new screening. I hope this helps others.

Well, that's a new one. Thanks for posting!

Wow. This thread saved my sanity! We bought a new house a little under 2 years ago. It was summer and I did some work on the house before we moved in. I reinstalled some screens that were stored in the basement so I could open the windows.

Months later as we got into winter, we began to smell an odd odor. It reminded me of diesel exhaust. It wafted through certain rooms. For 18 months I searched for the source. It was driving me crazy. I kept logs of the times I smelled it and the only pattern I could discern was that it seemed to be present at certain times of the day (from about 10am to the afternoon) and only when it was sunny and mostly in the winter. I couldn't figure it out, though. I walked around the attic, pulled ceiling tiles in the basement, sealed Windows, etc.. I searched the Internet for hours and hours.

Upon finally finding and reading this thread I put 2 and 2 together... I thought no way - it couldn't be the screens! But, it added up. We are in MI and the rooms that I smelled it in had south facing windows. So, the sun beamed in them in the winter months.

i figured it was worth a try, so I removed the screens from all south facing windows now, after 2 weeks the smell has completely disappeared. And, we've had plenty of days with the conditions that always led to the smell.

I can only say.. Thank you, Internet... And, mostly, thank you barcode_bill! I don't think I ever would have isolated screens as the cause of the smell, but that was it.

There is a sweet pungent smell in my bedroom, cannot figure it out. Keep cleaning bed linens, etc. Any suggestions?

I noticed a strong fishy odor in my bathroom just this morning. . I checked out all possibilities of sources, but could fine nothing. As the morning went on, the odor started radiating to the bedroom, then the hall, then the whole house and in my clothing! I feared a gas leak,so called, but It was not a gas leak. The service person said he had never smelled anything like it and agreed it smelled like 3 day old fish. Called the exterminator, who said it smelled like sardines! Close! He checked under the house and in the attic.. nothing. He checked the entire house and couldn't come up with an answer. He said it may be a lizard. It has nothing to do with the sun. It's a very cloudy drizzley day, so that's out. I don't know what to do next. Reading this post, I decided it may be the burning wires, ,so I opened up the outlets in the bathroom ,where it started, but it doesn't look burned. I also checked the breaker box. I am 85 years old and can't afford to hire all the different service people to "guess" what the problem is as one person did. So far I've checked for gas leaks and dead animals, but no answers. The burning wires seems to be the best answer, and I will call an electrician tomorrow, and hope he can solve it. It burns my eyes and nose and makes me a little leery going to bed. At least I know it's not gas.

Sounds like your outlets were not overheating, what about light fixtures? They don't necessarily have to be turned on to overheat. The power line usually goes to the fixture, then connects back down to the wall switch and back up to the fixture. So that connection could be failing inside the fixture. Or if the switch is ON the fixture, like a pull chain, the switch can be overheating. Or of course the socket itself when it's turned on. Make sure you don't have bulbs of too high a wattage in any of your fixtures.

I got an electrician, Showed him where it had started in the bathroom. Unfortunately I had put candles all over the house and the odor was almost gone. He was about to leave when we started plugging things in, including my curling iron. In less than five minutes the odor was stronger than ever. It was the curling iron! It was getting so hot the plastic part that protects your fingers was almost melted. It didn't matter that we turned it right off, as I had always done. The odor, I think got caught up in the heat vent and was all over the house again, in a matter of minutes. So check all of your plug ins. We had unplugged it and smelled the end. I said it might have a hint of the odor. Then I turned it on. Wow! It spread like wildfire. I'm glad it didn't catch on fire while I was sleeping. Thanks for all the postings. It was the only logical answer. Thanks Google. (But even Siri knew. The Electrician just said, "Siri, fishy smell in bathroom."And Siri explained the whole thing.) Isn't technology great! And, by the way, he was so happy about learning about this, he didn't charge me! He had never heard of it!

SORTED! I have had a bad "urine" type smell in an upstairs bedroom. Checked the cavity, no mice or squirrels! It turn out to be the UPVc double glazing. The bottom seal was letting water in from internal condensation. This collects in a bottom drip tray (under the glass and seal) and after time, STINKS! When the sun warms it up it smells more! I popped the bottom runner off, cleaned it out and all is good. Hope that helps.

My awful fish smell turned out to be my curling iron. Seeing a posting here, I called the electrcian. He could smell it ,but checked all the outlets and plugs and found nothing. He was getting ready to leave when I picked up the curling iron and smelled it, and it seemed to have that fish odor. Sure enough , the plastic part of it had been slowly burning and melting when I used it and continued even after it was turned off. We turned it on and the smell got very strong. I threw it out and got a new one. No more smell!

Mark Allen thank you sooo much. I created this account just to thank you. The smell was driving me insane because I couldn’t figure it out!

The dead animal or fishy smell can often be an older type of plastic that has heat up. In our 1960 house there are plastic sleeves around the base of the light fittings and once warmed up (5+ mins) they start to stink like there's a dead animal up there. I assume there is an organic component to the plastic that has broken down over time.

Not just old plastics. It appears outlets are made of polymerized melamine + formaldehyde. The 'amine' in melamine indicates nitrogen containing, and in fact melamine has a lot of N. C3H6N6 for you fellow nerds. This means it can degrade into nitrogen compounds which typically have pretty strong odors. This explains how a melting switch or outlet can smell fishy (plenty of nitrogen compounds in decomposing fish too...).

Well one more home owner battling this ”electrical, burning plastic, dead animal“ smell. The story starts with an odor we thought was originating from a WEEPING light switch! Yep, to the point one could see a trickle of water going down the wall from the light switch. Upon taking the light switch off the wires and inside casing was completely dry! However the inside of the switch plate had condensation. Fast forward after an electrician checked the wiring and found it ok, we proceeded to have the dishwasher replaced (it was below this light switch), new countertop, had the heat pump installer disinfectant the duct work, seal everything and attach a device that detects mold, inspect the crawl space ( no mold no dead animals), resealed outside electrical outlet and light fixture . They smell was obviously worse with the switch plate off when the heat or air came on. Odor seemed to subside after the effort to correct...switch plate has no condensation, but NOW it’s back!!! The switch plate still smells!! After reading these post, we’ll replace that light switch housing and check every light fixture. Thank you everyone’s post and endurung my rambling.

Wow I'm so happy I came across this post as I'm having this problem as i type and the only thing I was looking for was that the smell starts when the sun comes out. I've been searching Google for the past week on this issue that I'm having with this weird musty wood chemical smell that seems to only start when the Sun starts to rise!! Which is weird but we have a travel trailer and it has a solar panel system and the solar panel is no longer on the numbers are no longer on the solar panel system menu now the only time it's on showing the numbers is in the nighttime in the daytime there are no longer there so I don't know if it's a solar panels

Skunk got under the house, and had babies. Now, everytime the heater or air conditioner comes on, the smell coming from the vents is terrible. Smells like skunk, dead animal. Just plain rotten smell. How can we be rid of the smell?

Can you smell it outside the house, or only inside? There are two possible things happening here. First, if you have ducts under there (crawlspace) they may have sprayed or gotten stuff on the ducts and it's being sucked in. Second, when you turn on the heat in cold weather, a building creates a 'chimney effect' which draws a slight vacuum underneath it, and it can pull in vapors from the ground through cracks and crevices in the foundation. If it's the latter, no amount of cleaning ducts will help. You'd have to get rid of the source.

What kind of foundation is it, is there a crawlspace or are we talking about a concrete slab that they dug under?

For years we had a dead animal smell appear at the far end of the basement. I took down trim and insulation looking for it. It made us crazy because it only happened when we went to that end and the smell took 10 minutes to fill the whole basement, enough stink to chase us out. Yesterday my wife said there was no smell after rearranging the basement for hours. Today I googled "smells" again and read this thread, then remembered I had changed several plastic light fixtures with porcelain a 2 months earlier. One had a cracked insulator prompting the changes. Wow. So far we can now turn on the lights at that end with no smell!

I read on a different site that I'm not finding now that someone said the issue was the window screens giving off the odor when the sun heated them up. I took off my 25 year old screens and for the first time, my bedroom with a southern exposure did not have that awful smell! The odor has not returned.. Other people had written on the other site with success as well. Hope this helps some of you.

Nancy 53024

@nancy - it was actually this very thread, but way back. I too, found it and posted how it worked for me (after months of searching) several years ago.

Thank you, your post was a lifesaver for me. I surprised and redeemed by all the other people with this same problem. These sites are so helpful.

I'm puzzled. There is a foul odour coming from my kitchen and bathroom drains/cabinets but no leaks! The same smell sometimes in the hallway of my apartment. It smells like refuse with a hint of smouldering rubber, sometimes woody, sometimes pooey. The apartment is dry and sunny most days and no visible mould. But this smell is there all the time and it's driving me crazy. I use the taps often so it can't be sewer gas.

After a year spent in my recently refurbished house with new floors, new plaster, new paint, I finally found the cause of a persistent, localised, not-burning, chlorine-like smell. It has been bothering me every day since moving in. It is the actual plastic that my brand new mains electrical sockets are made of. This is not a burning plastic or ozone smell associated with faulty electrical wiring or fixtures. It is purely the plastic odour of the material. I believe they were quite cheap but recommended by my electrician. I'm going to get all 20 of them changed.

Just wanted to say thank you! i have been looking for the source of an acrid odor in my home for months Came across this thread, replaced all of my light bulbs and it is gone!

glad that worked for you. I learned on this site that it was the window screens for some and that was exactly my problem, even though my screens were 20 years old. The awful smell that came when the sun hit the windows in that one bedroom is gone. Nancy

Ali Nichol did you ever figure out what was causing the odor? We're having the exact same issue in a house we recently purchased. It's not screens, it's not ptraps or drains, nothing appears to be wrong, but the kitchen area has a subtle rotten odor which we cannot seem to eliminate. I have searched/cleaned/done everything in there I can think of and nada. I'm going to try the roof vent idea someone posted above. Other than that... I'm at a loss. I'm trying to mask it at this point with deodorizor but I'm also thinking it's time to call a plumber. :/

Just wanted to add my thanks, @barcode_bill! I just googled looking for why my living room often smells slightly odd but only in the afternoon when sunny…bet it’s the screens!